1. Field of the Invention
The present invention relates to a telescopic shaft in which an inner shaft is axially spline fitted within an outer shaft.
2. Description of the Prior Art
Conventional telescopic shafts are shown in U.S. Pat. Nos. 3,318,170, 3,434,369 and 3,434,368. In U.S. Pat. No. 3,434,368, an inner shaft is telescopically disposed within an outer shaft. The two shafts are connected by an axially extending serration or spline arrangement to prevent relative rotation. The shafts may be fixed at a desired position to prevent relative axial translation by depressing an outer circumferential surface of an end portion of the inner shaft against an inner circumferential surface of the outer shaft. U.S. Pat. No. 3,318,170 shows a telescopic shaft arrangement in which a sliding unit is provided near the end of one shaft and is depressed against the other shaft by an elastic member.
Splined shafts are constructed so that there is clearance between the mating portions when assembled to allow the shafts to slide without binding. However this clearance causes lost motion between the shafts. The known arrangements prevent some torsional lost motion between the inner and outer shafts but are ineffective in completely preventing all lost motion between the shafts in the torsional and bending directions.
An object of the present invention, therefore, is to provide an improved telescopic shaft which obviates the aforementioned drawbacks of the described conventional telescopic shaft by completely preventing all lost motion between the inner and outer shafts in the torsional and bending directions.
A further object of the present invention is to provide an improved telescopic shaft which is suitable for a main shaft of a telescopic steering column for vehicles.
A still further object of the present invention is to provide an improved telescopic shaft which can be moved reliably in a relatively simple manner.
Additional objects and advantages of the invention will be set forth in the description which follows and in part will be obvious from the description, as may be learned by practice of the invention.